1. Technical Field
The present invention relates to a method and apparatus for collecting sterile samples of urine for analysis. More particularly, the present invention relates to positively isolating the forestream and midstream portions of a urine void so as to preclude contamination of the midstream portion by the forestream portion.
2. The Prior Art
In collecting urine samples for medical testing and analysis, it is important that the collected samples be as free from contaminants as possible. Contaminants in the urethra and other areas of the urinary tract render straightforward collection of sterile samples somewhat difficult. The problem of contamination is even greater for women patients than for men because of the location of the urethral opening just superior to the vaginal opening. Secretions and other contaminants which collect in the vaginal area, including the labia majora and labia minora, are a particularly troublesome source of urine specimen contamination. It is therefore desirable that the collected sample consist of a midstream portion of a urine void so that the urethra and other areas of the urinary tract, as well as the related portions of the vaginal area, can be flushed out by the initial or forestream portion of the void before the sample for analysis is passed for collection. However, midstream urine collection is not an easy procedure, primarily because it is difficult for a patient to interrupt a void stream so as to pass only part of the stream before the collecting sample. As a consequence, numerous devices have been proposed in the prior art for automatically collecting midstream portions of a urine void. Examples of these devices may be found in U.S. Pat. Nos. 3,583,388 (Hovick), 3,635,091 (Linzer, et al), 3,722,503 (Hovick), 3,750,647 (Gleason, et al.), 3,830,107 (Linzer, et al.), 3,943,770 (McDonald), 3,982,898 (McDonald), 4,040,791 (Kuntz), 4,094,020 (Franklin), 4,276,889 (Kuntz et al.) and 4,331,162 (Kuntz et al). In spite of these devices, problems still exist in the art of midstream urine collection.
Most, if not all, of the aforesaid prior art problems have been effectively solved by the method and apparatus described and illustrated in U.S. patent application Ser. No. 06/467,904 filed on the same date as the present patent application in the names of Joseph Lichtenstein and Vincent Valliancourt, which application is entitled "Sterile Urine Specimen Collection" and is assigned to the same assignee at the present invention. The disclosure in that patent application, which will hereafter be referred to as the Lichtenstein et al patent application, is expressly incorporated herein by reference in its entirety. One of the problems addressed by the Lichtenstein et al patent application is the intermixing of supposedly segregated forestream and midstream portions at a urine void in a collection apparatus. Specifically, many of the prior art midstream collection devices rely on directing the forestream portion of the void into a chamber and then diverting or overflowing the midstream portion into a specimen container when the urine level in the chamber reaches some predetermined level. In such devices, unless the assembly is held absolutely still, the forestream portion is jostled and tends to intermix to some degree with the diverted or overflowing midstream portion. This intermixing results in comtamination of the midstream portion by contaminants in the forestream portion. Even when the device is held substantially still, flow currents exist which can carry contaminants from the forestream portion to the midstream portion. This problem is mitigated significantly by the collection device described in the aforesaid Lichtenstein et al patent application. More particularly, in that device, a solid body of urine-absorbent material is placed in a forestream collection chamber to effectively immobilize the liquid and drastically reduce the aforesaid currents. However, there still remains a liquid/air interface at the top of the forestream collection chamber to which the midstream portion of a void is directed before it is overflowed into the midstream specimen collection container. Thus, even though the Lichtenstein et al approach severly reduces the contamination as compared to prior art devices, it is still possible that the contacts between the midstream portion and the top surface of the forestream portion can result in contamination of the midstream portion.
Another problem which is not fully solved in the aforesaid Lichtenstein, et al patent application concerns stearing or directing the initial or forestream portion of the void so that it does not flow toward the overflow outlets, but instead flows directly into the forestream collection chamber. Specifically, the Lichtenstein et al device includes a void-receiving funnel having a discharge spout which terminates at a level above the overflow outlets, but is of smaller diameter than the wall in which the overflow outlets are defined. Thus, if the unit is oriented substantially vertically, the liquid discharged from the funnel is directed into the forestream chamber and not through the overflow outlets. However, it is not always possible for the unit to be held substantially vertically in use and, under such circumstances, the discharge from the funnel can be directed through the overflow outlets.